Be careful with what you refuse - If you insist on your existing flights, you could be downgraded to economy with no comeback other than the 75% refund for that sector - it isn't obliged to do any more than reimburse for the downgrade
If you want to travel in business class , then I would seriously consider its offer - 3 sectors down to 2 sectors is a benefit - the AUS-PHL being in economy is an issue, but not as bad as a downgrade across the atlantic
Alternatively, if oversold, you may get offloaded and just rebooked on the 1st option it has out of ORD-DBV which may not be any better than what is currently on offer